The Crystal Shard - I believe this was the first effort of the now notable R.A. Salvatore. The introduction of the legendary Drizzt Do'Urden to the world. It is a middle-earth type fantasy world where elves and dwarves roam. Salvatore writes amazing sword fight scenes

The Monk - one of the very first 'gothic' novels. Anne Rice before there was an Anne Rice (but no vampires). Frankenstein before there was a Mary Shelley.

Watership Down - Well, not much I can say that isn't already known.

Siddhartha - Well-to-do famous dude gives it all up to discover the meaning of life. Travels around trying different things.